Common Sedimentary Minerals

When igneous rocks are exposed to weathering, many of their common minerals completely dissolve or partially dissolve and convert into clay minerals. As a result, olivine, pyroxene, plagioclase, amphibole, and biotite are uncommon in sedimentary rocks. Similarly, most distinctly metamorphic minerals either dissolve or disintegrate into particles too small to be readily noticed by a beginning geologist.

Thus, of the eight common igneous minerals, only quartz, K-feldspar, and muscovite are commonly seen in sedimentary rocks. These minerals are joined in sedimentary rocks by clay minerals, calcite, dolomite, gypsum, and halite. The clay minerals form during mineral weathering. The other four minerals are salts that precipitate as water evaporates. The elemental constituents of these salts are ultimately also derived from mineral weathering.

Pyrite is not a rock-forming mineral, but it is commonly present in sedimentary rocks that formed in or near seawater (oceans, lagoons, and coastal swamps).